Considering that FCA and PSA had its partnership in the van segment downsized, so nowadays the mid-size Euro van in the Fiat range is not based on the same project that resulted on the Peugeot Expert among other variants, a merge with PSA would sound quite surprising to me.
But anyway, FCA now owns a quite excessive amount of brands, just like GM did prior to its reorganization, so I wouldn't really hold my breath for a merge. Some strenghtening of the joint-venture for vans would seem more likely.